. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. ructing the scales of chords, ,tangents, and secants engraved on mathematical instru-ments is shown in the annexed figure. 1047. A trigonometrical canon {fig. .396.) is a tablewherein is given tlie length of the sine, tangent, andsecant to every degree and minute of the (|uadrant,compared with the radius, which is expressed by imityor 1 with any number of ciphers. The logarithms, more-over, of these sines, tangents, and secants, are tabulated,
. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. ructing the scales of chords, ,tangents, and secants engraved on mathematical instru-ments is shown in the annexed figure. 1047. A trigonometrical canon {fig. .396.) is a tablewherein is given tlie length of the sine, tangent, andsecant to every degree and minute of the (|uadrant,compared with the radius, which is expressed by imityor 1 with any number of ciphers. The logarithms, more-over, of these sines, tangents, and secants, are tabulated, sothat trigonometrial calculations are performed by onlyaddition and subtraction. Iables of this sort are pub-lished separately, and we su])posj the reader to be pro-vided witi them. 1048. Problem I. To compute the 7iatural sine and cosineof a given arc. The semiperiphery of a circle whose radius is ] isknown to be 3-141592653589793, &c.: we have then thefollowing proportion: — As the number of degrees or minutes in the semicircleIs to the degrees or minutes in the proposed arc,§0 is 314159265, &c. to the length of the said Fig. 396. Now the length of the arc baing denated by the letter n. and its sine and cosine by s and c,these two will be expressed by the two following series, viz. —
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